Gyrokinetic microinstability analysis of high-Ti and high-Te isotope plasmas in Large Helical Device

Abstract

Transport and confinement characteristics, and microinstabilities for high- and high- isotope plasmas in Large Helical Device are explored by using the gyrokinetic Vlasov simulation GKV with hydrogen isotope ions and real-mass kinetic electrons. The experimental data indicate that the thermal diffusivity is reduced in the deuterium-dominated plasmas, where the deviation from the gyro-Bohm scaling in the overall tendency and the strong anomaly of the electron heat transport are identified. Linear gyrokinetic analyses identify that the growth rates of the ion temperature gradient and trapped electron mode (TEM) instabilities in the deuterium plasmas are reduced due to the change in the profile gradients and/or the isotope ion mass, and the radial dependence of the mixing-length diffusivity is qualitatively consistent with the experimental tendency. Also, TEM-like turbulent fluctuations are examined by the using the phase contrast imaging measurement and the linear gyrokinetic calculation for the high- deuterium plasma.